# Docker diagnostics in Amazon ECS
Docker provides several diagnostic tools that help you troubleshoot problems with your containers and tasks. For more information about all of the available Docker command line utilities, see the [Docker CLI reference](https://docs.docker.com/reference/cli/docker/) in the Docker documentation. You can access the Docker command line utilities by connecting to a container instance using SSH.
The exit codes that Docker containers report can also provide some diagnostic information (for example, exit code 137 means that the container received a `SIGKILL` signal). For more information, see [Exit Status](https://docs.docker.com/reference/cli/docker/container/run/#exit-status) in the Docker documentation.
## List Docker containers in Amazon ECS
You can use the **docker ps** command on your container instance to list the running containers. In the following example, only the Amazon ECS container agent is running. For more information, see [docker ps](https://docs.docker.com/reference/cli/docker/#ps) in the Docker documentation.
```
docker ps
```
Output:
```
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
cee0d6986de0 amazon/amazon-ecs-agent:latest "/agent" 22 hours ago Up 22 hours 127.0.0.1:51678->51678/tcp ecs-agent
```
You can use the **docker ps -a** command to see all containers (even stopped or killed containers). This is helpful for listing containers that are unexpectedly stopping. In the following example, container `f7f1f8a7a245` exited 9 seconds ago, so it doesn't show up in a **docker ps** output without the `-a` flag.
```
docker ps -a
```
Output:
```
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
db4d48e411b1 amazon/ecs-emptyvolume-base:autogenerated "not-applicable" 19 seconds ago ecs-console-sample-app-static-6-internalecs-emptyvolume-source-c09288a6b0cba8a53700
f7f1f8a7a245 busybox:buildroot-2014.02 "\"sh -c '/bin/sh -c 22 hours ago Exited (137) 9 seconds ago ecs-console-sample-app-static-6-busybox-ce83ce978a87a890ab01
189a8ff4b5f0 httpd:2 "httpd-foreground" 22 hours ago Exited (137) 40 seconds ago ecs-console-sample-app-static-6-simple-app-86caf9bcabe3e9c61600
0c7dca9321e3 amazon/ecs-emptyvolume-base:autogenerated "not-applicable" 22 hours ago ecs-console-sample-app-static-6-internalecs-emptyvolume-source-90fefaa68498a8a80700
cee0d6986de0 amazon/amazon-ecs-agent:latest "/agent" 22 hours ago Up 22 hours 127.0.0.1:51678->51678/tcp ecs-agent
```
## View Docker Logs in Amazon ECS
You can view the `STDOUT` and `STDERR` streams for a container with the **docker logs** command. In this example, the logs are displayed for the *dc7240fe892a* container and piped through the **head** command for brevity. For more information, go to [docker logs](https://docs.docker.com/reference/cli/docker/#logs) in the Docker documentation.
**Note**
Docker logs are only available on the container instance if you are using the default `json` log driver. If you have configured your tasks to use the `awslogs` log driver, then your container logs are available in CloudWatch Logs. For more information, see [Send Amazon ECS logs to CloudWatch](using_awslogs.md).
```
docker logs dc7240fe892a | head
```
Output:
```
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 172.17.0.11. Set the 'ServerName' directive globally to suppress this message
AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 172.17.0.11. Set the 'ServerName' directive globally to suppress this message
[Thu Apr 23 19:48:36.956682 2015] [mpm_event:notice] [pid 1:tid 140327115417472] AH00489: Apache/2.4.12 (Unix) configured -- resuming normal operations
[Thu Apr 23 19:48:36.956827 2015] [core:notice] [pid 1:tid 140327115417472] AH00094: Command line: 'httpd -D FOREGROUND'
10.0.1.86 - - [23/Apr/2015:19:48:59 +0000] "GET / HTTP/1.1" 200 348
10.0.0.154 - - [23/Apr/2015:19:48:59 +0000] "GET / HTTP/1.1" 200 348
10.0.1.86 - - [23/Apr/2015:19:49:28 +0000] "GET / HTTP/1.1" 200 348
10.0.0.154 - - [23/Apr/2015:19:49:29 +0000] "GET / HTTP/1.1" 200 348
10.0.1.86 - - [23/Apr/2015:19:49:50 +0000] "-" 408 -
10.0.0.154 - - [23/Apr/2015:19:49:50 +0000] "-" 408 -
10.0.1.86 - - [23/Apr/2015:19:49:58 +0000] "GET / HTTP/1.1" 200 348
10.0.0.154 - - [23/Apr/2015:19:49:59 +0000] "GET / HTTP/1.1" 200 348
10.0.1.86 - - [23/Apr/2015:19:50:28 +0000] "GET / HTTP/1.1" 200 348
10.0.0.154 - - [23/Apr/2015:19:50:29 +0000] "GET / HTTP/1.1" 200 348
time="2015-04-23T20:11:20Z" level="fatal" msg="write /dev/stdout: broken pipe"
```
## Inspect Docker Containers in Amazon ECS
If you have the Docker ID of a container, you can inspect it with the **docker inspect** command. Inspecting containers provides the most detailed view of the environment in which a container was launched. For more information, see [docker inspect](https://docs.docker.com/reference/cli/docker/#inspect) in the Docker documentation.
```
docker inspect dc7240fe892a
```
Output:
```
[{
"AppArmorProfile": "",
"Args": [],
"Config": {
"AttachStderr": false,
"AttachStdin": false,
"AttachStdout": false,
"Cmd": [
"httpd-foreground"
],
"CpuShares": 10,
"Cpuset": "",
"Domainname": "",
"Entrypoint": null,
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/apache2/bin",
"HTTPD_PREFIX=/usr/local/apache2",
"HTTPD_VERSION=2.4.12",
"HTTPD_BZ2_URL=https://www.apache.org/dist/httpd/httpd-2.4.12.tar.bz2"
],
"ExposedPorts": {
"80/tcp": {}
},
"Hostname": "dc7240fe892a",
...
```