I did a bit of research on the topic and find the optimal solution for me - a script that I run before each deploy of my Firebase functions. The script scans my container images and:
- Keeps the ones with
latest tag.
- Deletes all the images except the last too.
This approach is semi-automated. The storage anyway grows only when I deploy so it works really well for me.
The script is written in JavaScript for environment with node and gcloud cli available.
const spawn = require("child_process").spawn;
const KEEP_AT_LEAST = 2;
const CONTAINER_REGISTRIES = [
"gcr.io/<your project name>",
"eu.gcr.io/<your project name>/gcf/europe-west3"
];
async function go(registry) {
console.log(`> ${registry}`);
const images = await command(`gcloud`, [
"container",
"images",
"list",
`--repository=${registry}`,
"--format=json",
]);
for (let i = 0; i < images.length; i++) {
console.log(` ${images[i].name}`);
const image = images[i].name;
let tags = await command(`gcloud`, [
"container",
"images",
"list-tags",
image,
"--format=json",
]);
const totalImages = tags.length;
// do not touch `latest`
tags = tags.filter(({ tags }) => !tags.find((tag) => tag === "latest"));
// sorting by date
tags.sort((a, b) => {
const d1 = new Date(a.timestamp.datetime);
const d2 = new Date(b.timestamp.datetime);
return d2.getTime() - d1.getTime();
});
// keeping at least X number of images
tags = tags.filter((_, i) => i >= KEEP_AT_LEAST);
console.log(` For removal: ${tags.length}/${totalImages}`);
for (let j = 0; j < tags.length; j++) {
console.log(
` Deleting: ${formatImageTimestamp(tags[j])} | ${tags[j].digest}`
);
await command("gcloud", [
"container",
"images",
"delete",
`${image}@${tags[j].digest}`,
"--format=json",
"--quiet",
"--force-delete-tags",
]);
}
}
}
function command(cmd, args) {
return new Promise((done, reject) => {
const ps = spawn(cmd, args);
let result = "";
ps.stdout.on("data", (data) => {
result += data;
});
ps.stderr.on("data", (data) => {
result += data;
});
ps.on("close", (code) => {
if (code !== 0) {
console.log(`process exited with code ${code}`);
}
try {
done(JSON.parse(result));
} catch (err) {
done(result);
}
});
});
}
function formatImageTimestamp(image) {
const { year, month, day, hour, minute } = image.timestamp;
return `${year}-${month}-${day} ${hour}:${minute}`;
}
(async function () {
for (let i = 0; i < CONTAINER_REGISTRIES.length; i++) {
await go(CONTAINER_REGISTRIES[i]);
}
})();
It runs the following commands:
# finding images
gcloud container images list --repository=<your repository>
# getting metadata
gcloud container images list-tags <image name>
# deleting images
gcloud container images delete <image name>@<digest> --quiet --force-delete-tags
A blog post describing my findings is available here https://krasimirtsonev.com/blog/article/firebase-gcp-saving-money
