![]() ![]() The logs command prints the container’s entire log output to your terminal. You can use docker ps -a to get the IDs and names of your containers. ![]() ![]() With this tool at the ready, you can better see what’s going on with your containers. To view container logs, use the docker logs command: docker logs my-container Replace my-container with the name or ID of the container you want to inspect. Give these options a try and see how you can best customize your log viewing to suit your needs. If you issue the command docker logs –help, you’ll see that there are more options available than just tail. Now we can see it’s possible to get plenty of information regarding a container - enough information to troubleshoot what may be going on. The results of the command can be seen in Figure D. Where 692a was the first four characters in the Debian container ID. On another terminal, I issued the command: I spun up a Debian container, with the command: And don’t think this method works with only web-based containers. Once you have the container id, then use the logs command like below to get the logs. Get the container id from the list of running containers first. To access logs in a container, first we will have to identify the id of the running container. Using this method will make it significantly easier for you to troubleshoot your containers. In this article, we will see how to check docker container logs. To do this (again, sticking with our Shipyard example), the command would then look like:Īt this point, tail would follow the log file and present the last 10 lines of output as it is written ( Figure C). You can, however, make use of the tail command, such that you can view the log files being written as they happen. When you’re attempting to troubleshoot a container, that command isn’t going to help you all that much. If, on the other hand, you issue the following command, you’ll get results.Īs you can see ( Figure B), there are logs to be viewed for the Shipyard container. The above command would produce an error indicating no container named “shipyard” exists (whereas, issuing the same command for a running nginx container would actually work). Debugging and finding the root cause of problems can be done using log files. Docker generates the logs to the STDOUT or STDERR, including log origin, output stream data, and timestamp. Whenever an event occurs, the Docker container creates log files. Say you want to view the Shipyard logs you could issue the command: Log files generated by Docker containers contain a variety of useful information. Where CONTAINER is the name of the container you want to use. Viewing the Docker logs for a container is handled with the command: I use Shipyard for a specific purpose (one I’ll mention in a moment). The docker ps command shows me those names are: In my case, I’m looking for the names associated with Shipyard. The above command will output something similar to that in Figure A. To find out the name and ID, I’ll issue the command: For demonstration purposes, I will use Shipyard as my container. There are two “names” you can use for logging purposes: the container ID or the image name. Docker Driver Client Grafana Loki officially supports a Docker plugin that will read logs from Docker containers and ship them to Loki. In order to view a container’s logs, you must know the name of the container in question. With that said, let’s take a look at the best method of viewing your container’s log file. It should be noted, however, that logs are only written for running containers (you can view log files from stopped containers as well). You’ll be surprised how easy it is to view your container’s log file. Once you know how to start using this tool, it’ll make troubleshooting Docker containers significantly easier. I want to walk you through the process of working with Docker logs. Go-to resources for safe, secure cloud storage (TechRepublic Premium).Become a Microsoft Azure administrator online and start a great career.The vanilla approach: How open source helps deliver multicloud success.Cloud security: How your public cloud environment may be vulnerable to data breach.But how do you check a log file for a container that doesn’t contain a complete operating system? Fortunately, the developers of Docker have thought of just that. When that happens, what do you do? As with any piece of mission-critical software, any IT pro worth their weight in Cat5 will say the first thing you do is check the log files. Here's how to make it work for you.Ĭhances are you’ve run into issues with a Docker container or two. If you're looking for an easy way to troubleshoot your Docker containers, look no further than the docker logs command. ![]()
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