CRI-O

    In the sections below, we will explain the steps in the quick start scripts.

    Use the following commands to install CRI-O on your system.

    CRI-O uses the runtime by default and we need to configure it to use crun instead. That is done by adding to two configuration files.

    First, create a /etc/crio/crio.conf file and add the following lines as its content. It tells CRI-O to use crun by default.

    1. [crio.runtime]
    2. default_runtime = "crun"
    1. [crio.runtime.runtimes.runc]
    2. runtime_path = "/usr/lib/cri-o-runc/sbin/runc"
    3. runtime_type = "oci"
    4. runtime_root = "/run/runc"
    5. # The above is the original content
    7. # Add our crunw runtime here
    8. [crio.runtime.runtimes.crun]
    9. runtime_path = "/usr/bin/crun"
    10. runtime_type = "oci"
    11. runtime_root = "/run/crun"

    Next, restart CRI-O to apply the configuration changes.

    1. systemctl restart crio

    Now, we can run a simple WebAssembly program using CRI-O. explains how to compile, package, and publish the WebAssembly program as a container image to Docker hub. In this section, we will start off pulling this WebAssembly-based container image from Docker hub using CRI-O tools.

    Next, we need to create two simple configuration files that specifies how CRI-O should run this WebAssembly image in a sandbox. We already have those two files container_wasi.json and . You can just download them to your local directory as follows.

    1. wget https://raw.githubusercontent.com/second-state/wasmedge-containers-examples/main/crio/sandbox_config.json
    2. wget https://raw.githubusercontent.com/second-state/wasmedge-containers-examples/main/crio/container_wasi.json

    Now you can use CRI-O to create a pod and a container using the specified configurations.

    1. # Create the POD. Output will be different from example.
    2. $ sudo crictl runp sandbox_config.json
    3. 7992e75df00cc1cf4bff8bff660718139e3ad973c7180baceb9c84d074b516a4
    4. # Set a helper variable for later use.
    5. $ POD_ID=7992e75df00cc1cf4bff8bff660718139e3ad973c7180baceb9c84d074b516a4
    7. # Create the container instance. Output will be different from example.
    8. $ sudo crictl create $POD_ID container_wasi.json sandbox_config.json
    9. # Set a helper variable for later use.
    10. CONTAINER_ID=1d056e4a8a168f0c76af122d42c98510670255b16242e81f8e8bce8bd3a4476f

    Starting the container would execute the WebAssembly program. You can see the output in the console.

    1. # List the container, the state should be `Created`
    2. CONTAINER           IMAGE                                          CREATED              STATE               NAME                     ATTEMPT             POD ID
    3. 1d056e4a8a168       hydai/wasm-wasi-example:with-wasm-annotation   About a minute ago   Created             podsandbox1-wasm-wasi   0                   7992e75df00cc
    5. # Start the container
    8. # Check the container status again.
    9. # If the container is not finishing its job, you will see the Running state
    10. # Because this example is very tiny. You may see Exited at this moment.
    11. $ sudo crictl ps -a
    12. CONTAINER           IMAGE                                          CREATED              STATE               NAME                     ATTEMPT             POD ID
    13. 1d056e4a8a168       hydai/wasm-wasi-example:with-wasm-annotation   About a minute ago   Running             podsandbox1-wasm-wasi   0                   7992e75df00cc
    15. # When the container is finished. You can see the state becomes Exited.
    16. $ sudo crictl ps -a
    17. CONTAINER           IMAGE                                          CREATED              STATE               NAME                     ATTEMPT             POD ID
    18. 1d056e4a8a168       hydai/wasm-wasi-example:with-wasm-annotation   About a minute ago   Exited              podsandbox1-wasm-wasi   0                   7992e75df00cc
    20. # Check the container's logs. It should show outputs from the WebAssembly programs
    21. $ sudo crictl logs $CONTAINER_ID
    23. Test 1: Print Random Number
    24. Random number: 960251471
    26. Test 2: Print Random Bytes
    27. Random bytes: [50, 222, 62, 128, 120, 26, 64, 42, 210, 137, 176, 90, 60, 24, 183, 56, 150, 35, 209, 211, 141, 146, 2, 61, 215, 167, 194, 1, 15, 44, 156, 27, 179, 23, 241, 138, 71, 32, 173, 159, 180, 21, 198, 197, 247, 80, 35, 75, 245, 31, 6, 246, 23, 54, 9, 192, 3, 103, 72, 186, 39, 182, 248, 80, 146, 70, 244, 28, 166, 197, 17, 42, 109, 245, 83, 35, 106, 130, 233, 143, 90, 78, 155, 29, 230, 34, 58, 49, 234, 230, 145, 119, 83, 44, 111, 57, 164, 82, 120, 183, 194, 201, 133, 106, 3, 73, 164, 155, 224, 218, 73, 31, 54, 28, 124, 2, 38, 253, 114, 222, 217, 202, 59, 138, 155, 71, 178, 113]
    29. Test 3: Call an echo function
    30. Printed from wasi: This is from a main function
    31. This is from a main function
    33. Test 4: Print Environment Variables
    34. The env vars are as follows.
    35. PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    36. TERM: xterm
    37. HOSTNAME: crictl_host
    38. PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
    39. The args are as follows.
    40. 50000000
    42. Test 5: Create a file `/tmp.txt` with content `This is in a file`
    44. Test 6: Read the content from the previous file
    45. File content is This is in a file
    47. Test 7: Delete the previous file

    Finally, we can run a simple WebAssembly-based HTTP micro-service in CRI-O. A separate article explains how to compile, package, and publish the WebAssembly program as a container image to Docker hub. In this section, we will start off pulling this WebAssembly-based container image from Docker hub using CRI-O tools.

    Next, we need to create two simple configuration files that specifies how CRI-O should run this WebAssembly image in a sandbox. We already have those two files and sandbox_config.json. You can just download them to your local directory as follows.

    The sandbox_config.json file is the same for the simple WASI example and the HTTP server example. The other container_*.json file is application specific as it contains the application’s Docker Hub URL.

    1. wget https://raw.githubusercontent.com/second-state/wasmedge-containers-examples/main/crio/sandbox_config.json
    2. wget https://raw.githubusercontent.com/second-state/wasmedge-containers-examples/main/crio/http_server/container_http_server.json

    Now you can use CRI-O to create a pod and a container using the specified configurations.

    1. # Create the POD. Output will be different from example.
    2. $ sudo crictl runp sandbox_config.json
    3. 7992e75df00cc1cf4bff8bff660718139e3ad973c7180baceb9c84d074b516a4
    4. # Set a helper variable for later use.
    5. $ POD_ID=7992e75df00cc1cf4bff8bff660718139e3ad973c7180baceb9c84d074b516a4
    7. # Create the container instance. Output will be different from example.
    8. $ sudo crictl create $POD_ID container_http_server.json sandbox_config.json
    9. # Set a helper variable for later use.
    10. CONTAINER_ID=1d056e4a8a168f0c76af122d42c98510670255b16242e81f8e8bce8bd3a4476f

    Starting the container would execute the WebAssembly program. You can see the output in the console.

    1. # Start the container
    2. $ sudo crictl start $CONTAINER_ID
    4. # Check the container status. It should be Running. 
    5. # If not, wait a few seconds and check again
    6. $ sudo crictl ps -a
    7. CONTAINER           IMAGE                                          CREATED                  STATE               NAME                ATTEMPT             POD ID
    8. 4eeddf8613691       avengermojo/http_server:with-wasm-annotation   Less than a second ago   Running             http_server         0                   1d84f30e7012e
    10. # Check the container's logs to see the HTTP server is listening at port 1234
    11. $ sudo crictl logs $CONTAINER_ID
    12. new connection at 1234
    14. # Get the IP address assigned to the container
    15. $ sudo crictl inspect $CONTAINER_ID | grep IP.0 | cut -d: -f 2 | cut -d'"' -f 2
    16. 10.85.0.2
    18. # Test the HTTP service at that IP address