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https://github.com/eexit/curl-healthchecker
A cURL HTTP-only ultra-slim binary Docker image provider for your FROM scratch Docker image healthchecks
https://github.com/eexit/curl-healthchecker
curl docker-image dockerfile health-check healthcheck
Last synced: 27 days ago
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A cURL HTTP-only ultra-slim binary Docker image provider for your FROM scratch Docker image healthchecks
- Host: GitHub
- URL: https://github.com/eexit/curl-healthchecker
- Owner: eexit
- Created: 2021-05-31T19:36:12.000Z (over 3 years ago)
- Default Branch: master
- Last Pushed: 2021-05-31T21:58:40.000Z (over 3 years ago)
- Last Synced: 2024-11-10T13:18:32.539Z (3 months ago)
- Topics: curl, docker-image, dockerfile, health-check, healthcheck
- Language: Dockerfile
- Homepage: https://hub.docker.com/repository/docker/eexit/curl-healthchecker
- Size: 1.95 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# cURL healthchecker [](https://hub.docker.com/repository/docker/eexit/curl-healthchecker)
Latelely, I'm trying to set-up `HEALTHCHECK` to my Docker images and since I have many Go projects that run from scratch, I needed to find a way to test the health of my Go APIs.
At first, I tried to compile and build a binary like this:
```go
package main
import (
"net/http"
"os"
)
func main() {
code := 0
resp, err := http.Head("http://localhost/healthcheck")
if err != nil || resp.StatusCode != http.StatusOK || resp.StatusCode != http.StatusNoContent {
code = 1
}
os.Exit(code)
}
```
But even after compression (using [upx](https://upx.github.io/)), the binary is still 3.3M. Still too much for what it is.
After some digging and testing, I managed to build my own cURL binary with the bare mininum to handle a basic HTTP healthcheck request:
```bash
$ docker run --rm eexit/curl-healthchecker:v1.0.0 -V
curl 7.77.0 (x86_64-pc-linux-musl) libcurl/7.77.0
Release-Date: 2021-05-26
Protocols: http
Features: Largefile
```
The binary size is 194K, which is pretty slim.
## Usage
You only need to add 3 lines in your Dockerfile:
```dockerfile
FROM eexit/curl-healthchecker:v1.0.0 AS curl
# Other stages...
FROM scratch
COPY --from=curl /curl /
# Copy from other stages...
# Supposed your healthcheck endpoint is http://127.0.0.1/healthcheck
HEALTHCHECK --interval=5s --timeout=2s --retries=3 \
CMD ["/curl", "-fIA", "cURL healthcheck", "http://127.0.0.1/healthcheck"]
```
Once you've up'd your container, the health status is shown in the `docker ps` output:
```
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f6429b2318d3 eexit/http2smtp "/http2smtp" 29 seconds ago Up 26 seconds (healthy) 80/tcp, 0.0.0.0:80->8080/tcp, :::80->8080/tcp http2smtp_http2smtp_1
```
If you wish to troubleshoot:
```bash
docker inspect --format "{{json .State.Health }}" f6429b2318d3 | jq .
{
"Status": "healthy",
"FailingStreak": 0,
"Log": [
{
"Start": "2021-05-31T20:34:47.239507658Z",
"End": "2021-05-31T20:34:47.328378157Z",
"ExitCode": 0,
"Output": " % Total % Received % Xferd Average Speed Time Time Time Current\n Dload Upload Total Spent Left Speed\n\r 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0\r 0 25 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0\nHTTP/1.1 200 OK\r\nContent-Type: application/json\r\nDate: Mon, 31 May 2021 20:34:47 GMT\r\nContent-Length: 25\r\n\r\n"
}
]
}
```
---
Inspired from:
- https://medium.com/axiomzenteam/combining-docker-multi-stage-builds-and-health-checks-feea7cd2d85e
- https://github.com/hectorm/docker-curl
- https://github.com/moparisthebest/static-curl
- https://github.com/dtschan/curl-static
- https://github.com/curl/curl