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LICENSE
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README.md

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docker2singularity

This is an alternative implementation of docker2singularity that does not rely on Docker in Docker and granting the container full host device root capabilities via the --privileged flag.

(Which should in general be done only if absolutely necessary, could be considered bad practice, and turned out not to be necessary for the local container build workflows described below.)

Use cases

Singularity build

Build a Singularity image from a locally build Docker image,

$ docker pull kathoef/docker2singularity:latest
$ docker build -f Dockerfile -t localhost/test .
$ docker run --rm -v /var/run/docker.sock:/var/run/docker.sock:ro -v ${PWD}:/output \
kathoef/docker2singularity singularity build test.sif docker-daemon://localhost/test:latest

Singularity pull

Build a Singularity image from a remotely hosted Docker image,

$ docker pull kathoef/docker2singularity:latest
$ docker run --rm -v ${PWD}:/output \
kathoef/docker2singularity singularity pull alpine_latest.sif docker://alpine:latest

Compatibility

These workflows were tested on Linux, MacOS Mojave and Windows 10 (w/ Hyper-V backend) and Docker Desktop with Docker Engine v20.10.6 installed.

For Linux hosts

You might want to fix the Singularity image file ownership after conversion,

$ ls -l test.sif
-rwxr-xr-x 1 root root 2777088 Mai 15 17:19 test.sif
$ sudo chown $(id -u):$(id -g) test.sif
$ ls -l test.sif
-rwxr-xr-x 1 kathoef kathoef 2777088 Mai 15 17:19 test.sif

Background information

The Docker image provided here was originally specified for container image portability tests in order to have a fully controllable Singularity pull environment available.

It turned out that my local Docker image Singularity build tasks also worked quite well and only required the Docker socket to be mounted as read-only.

Since I use these Docker-based local Singularity container image build workflows quite often 1 I thought I'd provide a bit of a structured ground to this approach. Maybe it happens to be useful to others, feedback is welcome!

References

Singularity/Apptainer,

Multi-architecture build,

Footnotes

  1. mainly since CI and/or manual DockerHub-based workflows add complexity to a single-user data analysis project that seems unnecessary and also because I have seen singularity pull attempts on e.g. HPC machines failing ↩

About

pocket knife tool for Docker to Singularity image conversion tasks

Resources

Readme
MIT license
Activity

Stars

3 stars

Watchers

1 watching

Forks

2 forks
Report repository

Releases

Contributors

Languages

, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

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docker2singularity
This is an alternative implementation of docker2singularity that does not rely on Docker in Docker and granting the container full host device root capabilities via the --privileged flag.
(Which should in general be done only if absolutely necessary, could be considered bad practice, and turned out not to be necessary for the local container build workflows described below.)
Use cases
Singularity build
Build a Singularity image from a locally build Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker build -f Dockerfile -t localhost/test .
$ docker run --rm -v /var/run/docker.sock:/var/run/docker.sock:ro -v ${PWD}:/output \
kathoef/docker2singularity singularity build test.sif docker-daemon://localhost/test:latest

Singularity pull
Build a Singularity image from a remotely hosted Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker run --rm -v ${PWD}:/output \
kathoef/docker2singularity singularity pull alpine_latest.sif docker://alpine:latest

Compatibility
These workflows were tested on Linux, MacOS Mojave and Windows 10 (w/ Hyper-V backend) and Docker Desktop with Docker Engine v20.10.6 installed.
For Linux hosts
You might want to fix the Singularity image file ownership after conversion,
$ ls -l test.sif
-rwxr-xr-x 1 root root 2777088 Mai 15 17:19 test.sif
$ sudo chown $(id -u):$(id -g) test.sif
$ ls -l test.sif
-rwxr-xr-x 1 kathoef kathoef 2777088 Mai 15 17:19 test.sif

Background information
The Docker image provided here was originally specified for container image portability tests in order to have a fully controllable Singularity pull environment available.
It turned out that my local Docker image Singularity build tasks also worked quite well and only required the Docker socket to be mounted as read-only.
Since I use these Docker-based local Singularity container image build workflows quite often 1 I thought I'd provide a bit of a structured ground to this approach.
Maybe it happens to be useful to others, feedback is welcome!
References
Singularity/Apptainer,
Multi-architecture build,
Footnotes
  1. mainly since CI and/or manual DockerHub-based workflows add complexity to a single-user data analysis project that seems unnecessary and also because I have seen singularity pull attempts on e.g. HPC machines failing ↩
About
pocket knife tool for Docker to Singularity image conversion tasks
Resources
Readme
MIT license
Activity
Stars
3 stars
Watchers
1 watching
Forks
2 forks
Report repository
Releases
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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Repository files navigation
docker2singularity
This is an alternative implementation of docker2singularity that does not rely on Docker in Docker and granting the container full host device root capabilities via the --privileged flag.
(Which should in general be done only if absolutely necessary, could be considered bad practice, and turned out not to be necessary for the local container build workflows described below.)
Use cases
Singularity build
Build a Singularity image from a locally build Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker build -f Dockerfile -t localhost/test .
$ docker run --rm -v /var/run/docker.sock:/var/run/docker.sock:ro -v ${PWD}:/output \
kathoef/docker2singularity singularity build test.sif docker-daemon://localhost/test:latest

Singularity pull
Build a Singularity image from a remotely hosted Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker run --rm -v ${PWD}:/output \
kathoef/docker2singularity singularity pull alpine_latest.sif docker://alpine:latest

Compatibility
These workflows were tested on Linux, MacOS Mojave and Windows 10 (w/ Hyper-V backend) and Docker Desktop with Docker Engine v20.10.6 installed.
For Linux hosts
You might want to fix the Singularity image file ownership after conversion,
$ ls -l test.sif
-rwxr-xr-x 1 root root 2777088 Mai 15 17:19 test.sif
$ sudo chown $(id -u):$(id -g) test.sif
$ ls -l test.sif
-rwxr-xr-x 1 kathoef kathoef 2777088 Mai 15 17:19 test.sif

Background information
The Docker image provided here was originally specified for container image portability tests in order to have a fully controllable Singularity pull environment available.
It turned out that my local Docker image Singularity build tasks also worked quite well and only required the Docker socket to be mounted as read-only.
Since I use these Docker-based local Singularity container image build workflows quite often 1 I thought I'd provide a bit of a structured ground to this approach.
Maybe it happens to be useful to others, feedback is welcome!
References
Singularity/Apptainer,
Multi-architecture build,
Footnotes
  1. mainly since CI and/or manual DockerHub-based workflows add complexity to a single-user data analysis project that seems unnecessary and also because I have seen singularity pull attempts on e.g. HPC machines failing ↩
About
pocket knife tool for Docker to Singularity image conversion tasks
Resources
Readme
MIT license
Activity
Stars
3 stars
Watchers
1 watching
Forks
2 forks
Report repository
Releases
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
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LICENSE
LICENSE
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README.md
Repository files navigation
docker2singularity
This is an alternative implementation of docker2singularity that does not rely on Docker in Docker and granting the container full host device root capabilities via the --privileged flag.
(Which should in general be done only if absolutely necessary, could be considered bad practice, and turned out not to be necessary for the local container build workflows described below.)
Use cases
Singularity build
Build a Singularity image from a locally build Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker build -f Dockerfile -t localhost/test .
$ docker run --rm -v /var/run/docker.sock:/var/run/docker.sock:ro -v ${PWD}:/output \
kathoef/docker2singularity singularity build test.sif docker-daemon://localhost/test:latest

Singularity pull
Build a Singularity image from a remotely hosted Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker run --rm -v ${PWD}:/output \
kathoef/docker2singularity singularity pull alpine_latest.sif docker://alpine:latest

Compatibility
These workflows were tested on Linux, MacOS Mojave and Windows 10 (w/ Hyper-V backend) and Docker Desktop with Docker Engine v20.10.6 installed.
For Linux hosts
You might want to fix the Singularity image file ownership after conversion,
$ ls -l test.sif
-rwxr-xr-x 1 root root 2777088 Mai 15 17:19 test.sif
$ sudo chown $(id -u):$(id -g) test.sif
$ ls -l test.sif
-rwxr-xr-x 1 kathoef kathoef 2777088 Mai 15 17:19 test.sif

Background information
The Docker image provided here was originally specified for container image portability tests in order to have a fully controllable Singularity pull environment available.
It turned out that my local Docker image Singularity build tasks also worked quite well and only required the Docker socket to be mounted as read-only.
Since I use these Docker-based local Singularity container image build workflows quite often 1 I thought I'd provide a bit of a structured ground to this approach.
Maybe it happens to be useful to others, feedback is welcome!
References
Singularity/Apptainer,
Multi-architecture build,
Footnotes
  1. mainly since CI and/or manual DockerHub-based workflows add complexity to a single-user data analysis project that seems unnecessary and also because I have seen singularity pull attempts on e.g. HPC machines failing ↩
About
pocket knife tool for Docker to Singularity image conversion tasks
Resources
Readme
MIT license
Activity
Stars
3 stars
Watchers
1 watching
Forks
2 forks
Report repository
Releases
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
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17 Commits
Folders and files
NameName
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.dockerignore
.dockerignore
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Dockerfile
LICENSE
LICENSE
README.md
README.md
Repository files navigation
docker2singularity
This is an alternative implementation of docker2singularity that does not rely on Docker in Docker and granting the container full host device root capabilities via the --privileged flag.
(Which should in general be done only if absolutely necessary, could be considered bad practice, and turned out not to be necessary for the local container build workflows described below.)
Use cases
Singularity build
Build a Singularity image from a locally build Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker build -f Dockerfile -t localhost/test .
$ docker run --rm -v /var/run/docker.sock:/var/run/docker.sock:ro -v ${PWD}:/output \
kathoef/docker2singularity singularity build test.sif docker-daemon://localhost/test:latest

Singularity pull
Build a Singularity image from a remotely hosted Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker run --rm -v ${PWD}:/output \
kathoef/docker2singularity singularity pull alpine_latest.sif docker://alpine:latest

Compatibility
These workflows were tested on Linux, MacOS Mojave and Windows 10 (w/ Hyper-V backend) and Docker Desktop with Docker Engine v20.10.6 installed.
For Linux hosts
You might want to fix the Singularity image file ownership after conversion,
$ ls -l test.sif
-rwxr-xr-x 1 root root 2777088 Mai 15 17:19 test.sif
$ sudo chown $(id -u):$(id -g) test.sif
$ ls -l test.sif
-rwxr-xr-x 1 kathoef kathoef 2777088 Mai 15 17:19 test.sif

Background information
The Docker image provided here was originally specified for container image portability tests in order to have a fully controllable Singularity pull environment available.
It turned out that my local Docker image Singularity build tasks also worked quite well and only required the Docker socket to be mounted as read-only.
Since I use these Docker-based local Singularity container image build workflows quite often 1 I thought I'd provide a bit of a structured ground to this approach.
Maybe it happens to be useful to others, feedback is welcome!
References
Singularity/Apptainer,
Multi-architecture build,
Footnotes
  1. mainly since CI and/or manual DockerHub-based workflows add complexity to a single-user data analysis project that seems unnecessary and also because I have seen singularity pull attempts on e.g. HPC machines failing ↩
About
pocket knife tool for Docker to Singularity image conversion tasks
Resources
Readme
MIT license
Activity
Stars
3 stars
Watchers
1 watching
Forks
2 forks
Report repository
Releases
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
BranchesTags
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17 Commits
Folders and files
NameName
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Dockerfile
LICENSE
LICENSE
README.md
README.md
Repository files navigation
docker2singularity
This is an alternative implementation of docker2singularity that does not rely on Docker in Docker and granting the container full host device root capabilities via the --privileged flag.
(Which should in general be done only if absolutely necessary, could be considered bad practice, and turned out not to be necessary for the local container build workflows described below.)
Use cases
Singularity build
Build a Singularity image from a locally build Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker build -f Dockerfile -t localhost/test .
$ docker run --rm -v /var/run/docker.sock:/var/run/docker.sock:ro -v ${PWD}:/output \
kathoef/docker2singularity singularity build test.sif docker-daemon://localhost/test:latest

Singularity pull
Build a Singularity image from a remotely hosted Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker run --rm -v ${PWD}:/output \
kathoef/docker2singularity singularity pull alpine_latest.sif docker://alpine:latest

Compatibility
These workflows were tested on Linux, MacOS Mojave and Windows 10 (w/ Hyper-V backend) and Docker Desktop with Docker Engine v20.10.6 installed.
For Linux hosts
You might want to fix the Singularity image file ownership after conversion,
$ ls -l test.sif
-rwxr-xr-x 1 root root 2777088 Mai 15 17:19 test.sif
$ sudo chown $(id -u):$(id -g) test.sif
$ ls -l test.sif
-rwxr-xr-x 1 kathoef kathoef 2777088 Mai 15 17:19 test.sif

Background information
The Docker image provided here was originally specified for container image portability tests in order to have a fully controllable Singularity pull environment available.
It turned out that my local Docker image Singularity build tasks also worked quite well and only required the Docker socket to be mounted as read-only.
Since I use these Docker-based local Singularity container image build workflows quite often 1 I thought I'd provide a bit of a structured ground to this approach.
Maybe it happens to be useful to others, feedback is welcome!
References
Singularity/Apptainer,
Multi-architecture build,
Footnotes
  1. mainly since CI and/or manual DockerHub-based workflows add complexity to a single-user data analysis project that seems unnecessary and also because I have seen singularity pull attempts on e.g. HPC machines failing ↩
About
pocket knife tool for Docker to Singularity image conversion tasks
Resources
Readme
MIT license
Activity
Stars
3 stars
Watchers
1 watching
Forks
2 forks
Report repository
Releases
Contributors
Languages

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
BranchesTags
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17 Commits
Folders and files
NameName
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.github/workflows
.github/workflows
.dockerignore
.dockerignore
Dockerfile
Dockerfile
LICENSE
LICENSE
README.md
README.md
Repository files navigation
docker2singularity
This is an alternative implementation of docker2singularity that does not rely on Docker in Docker and granting the container full host device root capabilities via the --privileged flag.
(Which should in general be done only if absolutely necessary, could be considered bad practice, and turned out not to be necessary for the local container build workflows described below.)
Use cases
Singularity build
Build a Singularity image from a locally build Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker build -f Dockerfile -t localhost/test .
$ docker run --rm -v /var/run/docker.sock:/var/run/docker.sock:ro -v ${PWD}:/output \
kathoef/docker2singularity singularity build test.sif docker-daemon://localhost/test:latest

Singularity pull
Build a Singularity image from a remotely hosted Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker run --rm -v ${PWD}:/output \
kathoef/docker2singularity singularity pull alpine_latest.sif docker://alpine:latest

Compatibility
These workflows were tested on Linux, MacOS Mojave and Windows 10 (w/ Hyper-V backend) and Docker Desktop with Docker Engine v20.10.6 installed.
For Linux hosts
You might want to fix the Singularity image file ownership after conversion,
$ ls -l test.sif
-rwxr-xr-x 1 root root 2777088 Mai 15 17:19 test.sif
$ sudo chown $(id -u):$(id -g) test.sif
$ ls -l test.sif
-rwxr-xr-x 1 kathoef kathoef 2777088 Mai 15 17:19 test.sif

Background information
The Docker image provided here was originally specified for container image portability tests in order to have a fully controllable Singularity pull environment available.
It turned out that my local Docker image Singularity build tasks also worked quite well and only required the Docker socket to be mounted as read-only.
Since I use these Docker-based local Singularity container image build workflows quite often 1 I thought I'd provide a bit of a structured ground to this approach.
Maybe it happens to be useful to others, feedback is welcome!
References
Singularity/Apptainer,
Multi-architecture build,
Footnotes
  1. mainly since CI and/or manual DockerHub-based workflows add complexity to a single-user data analysis project that seems unnecessary and also because I have seen singularity pull attempts on e.g. HPC machines failing ↩
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pocket knife tool for Docker to Singularity image conversion tasks
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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docker2singularity
This is an alternative implementation of docker2singularity that does not rely on Docker in Docker and granting the container full host device root capabilities via the --privileged flag.
(Which should in general be done only if absolutely necessary, could be considered bad practice, and turned out not to be necessary for the local container build workflows described below.)
Use cases
Singularity build
Build a Singularity image from a locally build Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker build -f Dockerfile -t localhost/test .
$ docker run --rm -v /var/run/docker.sock:/var/run/docker.sock:ro -v ${PWD}:/output \
kathoef/docker2singularity singularity build test.sif docker-daemon://localhost/test:latest

Singularity pull
Build a Singularity image from a remotely hosted Docker image,
$ docker pull kathoef/docker2singularity:latest
$ docker run --rm -v ${PWD}:/output \
kathoef/docker2singularity singularity pull alpine_latest.sif docker://alpine:latest

Compatibility
These workflows were tested on Linux, MacOS Mojave and Windows 10 (w/ Hyper-V backend) and Docker Desktop with Docker Engine v20.10.6 installed.
For Linux hosts
You might want to fix the Singularity image file ownership after conversion,
$ ls -l test.sif
-rwxr-xr-x 1 root root 2777088 Mai 15 17:19 test.sif
$ sudo chown $(id -u):$(id -g) test.sif
$ ls -l test.sif
-rwxr-xr-x 1 kathoef kathoef 2777088 Mai 15 17:19 test.sif

Background information
The Docker image provided here was originally specified for container image portability tests in order to have a fully controllable Singularity pull environment available.
It turned out that my local Docker image Singularity build tasks also worked quite well and only required the Docker socket to be mounted as read-only.
Since I use these Docker-based local Singularity container image build workflows quite often 1 I thought I'd provide a bit of a structured ground to this approach.
Maybe it happens to be useful to others, feedback is welcome!
References
Singularity/Apptainer,
Multi-architecture build,
Footnotes
  1. mainly since CI and/or manual DockerHub-based workflows add complexity to a single-user data analysis project that seems unnecessary and also because I have seen singularity pull attempts on e.g. HPC machines failing ↩
About
pocket knife tool for Docker to Singularity image conversion tasks
Resources
Readme
MIT license
Activity
Stars
3 stars
Watchers
1 watching
Forks
2 forks
Report repository
Releases
Contributors
Languages