Complete step by step process for running wasm container.

This commit is contained in:
2023-01-31 22:48:03 +13:00
parent 29f98dc6f1
commit 7d7df24e72
2 changed files with 67 additions and 7 deletions

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@ -1,3 +1,3 @@
FROM scratch
COPY hello_wasm.wasm /
COPY hello_wasm/target/wasm32-wasi/debug/hello_wasm.wasm /
CMD ["/hello_wasm.wasm"]

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@ -3,7 +3,7 @@
#+DATE: <2023-01-31 Tue 13:00>
In our recent [[https://www.redhat.com/en/blog/red-hat-and-webassembly][blog post]] on Web Assembly we highlighted the implementation of WASM support into the [[https://github.com/containers/crun/][crun]] Open Container Initiative (OCI) runtime. This change paves the way for Podman and OpenShift to run WASM workloads.
In our recent [[https://www.redhat.com/en/blog/red-hat-and-webassembly][blog post]] on Web Assembly we highlighted the implementation of WASM support into the [[https://github.com/containers/crun/][crun]] Open Container Initiative (OCI) runtime. This change paves the way for Podman and OpenShift to run WASM workloads alongside our traditional container workloads.
This demo will step through how WASM modules can be run alongside traditional workloads in Podman.
@ -47,10 +47,7 @@ git clone https://github.com/containers/crun && cd crun
./autogen.sh
./configure --with-wasmedge
make
sudo make install
# Cleanup the crun source
cd ../ and rm -rf crun
sudo make install && cd ../ && rm -rf crun
#+end_src
@ -63,7 +60,6 @@ crun --version
The output should look something like the example below:
#+RESULTS: Check crun flags results
#+begin_src bash
crun version 1.7.2.0.0.0.80-940b
commit: 940bf973f144c81149cf05135f127ca6f0d19eb6
@ -71,3 +67,67 @@ rundir: /run/user/1000/crun
spec: 1.0.0
+SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +WASM:wasmedge +YAJL
#+end_src
* Compile a wasm example application
With our system setup let's compile a hello world in rust to ~.wasm~ so we can then run it with our container engine.
#+begin_src tmate :socket /tmp/james.tmate.tmate
# Create new rust project
rm -rf hello_wasm && cargo new hello_wasm --bin && cd hello_wasm
# Customise the main function
sed -i 's/world/openshift meetup/g' src/main.rs
cat src/main.rs
# Ensure we have rust wasm tooling installed
rustup target add wasm32-wasi
# Compile to the wasm target
cargo build --target wasm32-wasi
#+end_src
We can run it directly with our ~wasmedge~ runtime to verify everything worked.
#+NAME: Run wasm binary directly
#+begin_src tmate :socket /tmp/james.tmate.tmate
wasmedge target/wasm32-wasi/debug/hello_wasm.wasm
#+end_src
* Build a wasm container
Awesome, we have a compiled ~.wasm~ portable binary. Lets build this into an OCI compliant image so that our container engine can run it like a traditional container.
#+NAME: Build wasm container
#+begin_src tmate :socket /tmp/james.tmate.tmate
# Review contents of included containerfile
cd ../ && cat Containerfile
# Build the container with buildah
buildah build --annotation "module.wasm.image/variant=compat" -t mywasm-image .
#+end_src
The interesting thing about wasm container images is just how small they can potentially be as the image doesn't contain any operating system or libraries, literally just our portable ~.wasm~ file.
If we take a look at the image we just built it's only a couple of megabytes!
#+NAME: Check image size
#+begin_src tmate :socket /tmp/james.tmate.tmate
podman images | grep wasm
#+end_src
* Running a wasm container
Now that we have a container image built let's run it with Podman.
Note that we need to ensure Podman is pointing at our customised container runtime that has WASM support, this can be done via either configuration file or cli parameter.
#+NAME: Run container image
#+begin_src tmate
podman --runtime /usr/local/bin/crun run -t --rm localhost/mywasm-image:latest
#+end_src