azure Blob MD5 checksum and local MD5 checksum not matching

As discussed in the comments. Solution from here:

Googled around and found a suggestion to use openssl dgst, and it worked!

openssl dgst -md5 -binary $filename | base64

Turns out, md5sum returns a hex representation of the hash and I had to unhex it before computing its base64:

md5sum --binary $filename | awk '{print $1}' | xxd -p -r | base64