Commit c91168c0 authored by Achilleas Pipinellis's avatar Achilleas Pipinellis

Small refactor on Registry troubleshooting

[ci skip]
parent 2c9cce0f
...@@ -5,27 +5,27 @@ ...@@ -5,27 +5,27 @@
1. Check to make sure that the system clock on your Docker client and GitLab server have 1. Check to make sure that the system clock on your Docker client and GitLab server have
been synchronized (e.g. via NTP). been synchronized (e.g. via NTP).
2. If you are using an S3-backed registry, double check that the IAM 2. If you are using an S3-backed Registry, double check that the IAM
permissions and the S3 credentials (including region) are correct. See [the permissions and the S3 credentials (including region) are correct. See [the
sample IAM policy](https://docs.docker.com/registry/storage-drivers/s3/) sample IAM policy](https://docs.docker.com/registry/storage-drivers/s3/)
for more details. for more details.
3. Check the registry logs (e.g. `/var/log/gitlab/registry/current`) and the GitLab production logs 3. Check the Registry logs (e.g. `/var/log/gitlab/registry/current`) and the GitLab production logs
for errors (e.g. `/var/log/gitlab/gitlab-rails/production.log`). You may be able to find clues for errors (e.g. `/var/log/gitlab/gitlab-rails/production.log`). You may be able to find clues
there. there.
# Advanced Troubleshooting ## Advanced Troubleshooting
NOTE: The following section is only recommended for experts. >**NOTE:** The following section is only recommended for experts.
Sometimes it's not obvious what is wrong, and you may need to dive deeper into Sometimes it's not obvious what is wrong, and you may need to dive deeper into
the communication between the Docker client and the registry to find out the communication between the Docker client and the Registry to find out
what's wrong. We will use a concrete example in the past to illustrate how to what's wrong. We will use a concrete example in the past to illustrate how to
diagnose a problem with the S3 setup. diagnose a problem with the S3 setup.
## Example: Unexpected 403 error during push ### Unexpected 403 error during push
A user attempted to enable an S3-backed registry. The `docker login` step went A user attempted to enable an S3-backed Registry. The `docker login` step went
fine. However, when pushing an image, the output showed: fine. However, when pushing an image, the output showed:
``` ```
...@@ -44,11 +44,11 @@ error parsing HTTP 403 response body: unexpected end of JSON input: "" ...@@ -44,11 +44,11 @@ error parsing HTTP 403 response body: unexpected end of JSON input: ""
``` ```
This error is ambiguous, as it's not clear whether the 403 is coming from the This error is ambiguous, as it's not clear whether the 403 is coming from the
GitLab Rails application, the Docker registry, or something else. In this GitLab Rails application, the Docker Registry, or something else. In this
case, since we know that since the login succeeded, we probably need to look case, since we know that since the login succeeded, we probably need to look
at the communication between the client and the registry. at the communication between the client and the Registry.
The REST API between the Docker client and registry is [described The REST API between the Docker client and Registry is [described
here](https://docs.docker.com/registry/spec/api/). Normally, one would just here](https://docs.docker.com/registry/spec/api/). Normally, one would just
use Wireshark or tcpdump to capture the traffic and see where things went use Wireshark or tcpdump to capture the traffic and see where things went
wrong. However, since all communication between Docker clients and servers wrong. However, since all communication between Docker clients and servers
...@@ -56,12 +56,12 @@ are done over HTTPS, it's a bit difficult to decrypt the traffic quickly even ...@@ -56,12 +56,12 @@ are done over HTTPS, it's a bit difficult to decrypt the traffic quickly even
if you know the private key. What can we do instead? if you know the private key. What can we do instead?
One way would be to disable HTTPS by setting up an [insecure One way would be to disable HTTPS by setting up an [insecure
registry](https://docs.docker.com/registry/insecure/). This could introduce a Registry](https://docs.docker.com/registry/insecure/). This could introduce a
security hole and is only recommended for local testing. If you have a security hole and is only recommended for local testing. If you have a
production system and can't or don't want to do this, there is another way: production system and can't or don't want to do this, there is another way:
use mitmproxy, which stands for Man-in-the-Middle Proxy. use mitmproxy, which stands for Man-in-the-Middle Proxy.
## mitmproxy ### mitmproxy
[mitmproxy](https://mitmproxy.org/) allows you to place a proxy between your [mitmproxy](https://mitmproxy.org/) allows you to place a proxy between your
client and server to inspect all traffic. One wrinkle is that your system client and server to inspect all traffic. One wrinkle is that your system
...@@ -70,10 +70,9 @@ needs to trust the mitmproxy SSL certificates for this to work. ...@@ -70,10 +70,9 @@ needs to trust the mitmproxy SSL certificates for this to work.
The following installation instructions assume you are running Ubuntu: The following installation instructions assume you are running Ubuntu:
1. Install mitmproxy (see http://docs.mitmproxy.org/en/stable/install.html) 1. Install mitmproxy (see http://docs.mitmproxy.org/en/stable/install.html)
1. Run `mitmproxy --port 9000` to generate its certificates.
2. Run `mitmproxy --port 9000` to generate its certificates. Enter CTRL-C to quit. Enter <kbd>CTRL</kbd>-<kbd>C</kbd> to quit.
1. Install the certificate from `~/.mitmproxy` to your system:
3. Install the certificate from ~/.mitmproxy to your system:
```sh ```sh
sudo cp ~/.mitmproxy/mitmproxy-ca-cert.pem /usr/local/share/ca-certificates/mitmproxy-ca-cert.crt sudo cp ~/.mitmproxy/mitmproxy-ca-cert.pem /usr/local/share/ca-certificates/mitmproxy-ca-cert.crt
...@@ -87,24 +86,22 @@ Updating certificates in /etc/ssl/certs... 1 added, 0 removed; done. ...@@ -87,24 +86,22 @@ Updating certificates in /etc/ssl/certs... 1 added, 0 removed; done.
Running hooks in /etc/ca-certificates/update.d....done. Running hooks in /etc/ca-certificates/update.d....done.
``` ```
## Verifying mitmproxy certifiactes To verify that the certificates are properly installed, run:
To verify that the certificates are properly install, run:
```sh ```sh
mitmproxy --port 9000 mitmproxy --port 9000
``` ```
This will run mitmproxy on port 9000. In another window, run: This will run mitmproxy on port `9000`. In another window, run:
```sh ```sh
curl --proxy http://localhost:9000 https://httpbin.org/status/200 curl --proxy http://localhost:9000 https://httpbin.org/status/200
``` ```
If everything is setup correctly, then you will see information on the mitmproxy window and If everything is setup correctly, you will see information on the mitmproxy window and
no errors from the curl commands. no errors from the curl commands.
## Running the Docker daemon with a proxy ### Running the Docker daemon with a proxy
For Docker to connect through a proxy, you must start the Docker daemon with the For Docker to connect through a proxy, you must start the Docker daemon with the
proper environment variables. The easiest way is to shutdown Docker (e.g. `sudo initctl stop docker`) proper environment variables. The easiest way is to shutdown Docker (e.g. `sudo initctl stop docker`)
...@@ -118,10 +115,10 @@ docker daemon --debug ...@@ -118,10 +115,10 @@ docker daemon --debug
This will launch the Docker daemon and proxy all connections through mitmproxy. This will launch the Docker daemon and proxy all connections through mitmproxy.
## Running the Docker client ### Running the Docker client
Now that we have mitmproxy and Docker running, we can now attempt to login and push a container Now that we have mitmproxy and Docker running, we can attempt to login and push
image. You may need to run as root to do this. For example: a container image. You may need to run as root to do this. For example:
```sh ```sh
docker login s3-testing.myregistry.com:4567 docker login s3-testing.myregistry.com:4567
...@@ -141,4 +138,4 @@ The above image shows: ...@@ -141,4 +138,4 @@ The above image shows:
What does this mean? This strongly suggests that the S3 user does not have the right What does this mean? This strongly suggests that the S3 user does not have the right
[permissions to perform a HEAD request](http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectHEAD.html). [permissions to perform a HEAD request](http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectHEAD.html).
The solution: check the [IAM permissions again](https://docs.docker.com/registry/storage-drivers/s3/). The solution: check the [IAM permissions again](https://docs.docker.com/registry/storage-drivers/s3/).
Once the right permissions were set, the error went away. Once the right permissions were set, the error will go away.
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