[Ubuntu upgrade] Upgrade images to Ubuntu 20.04

[jonathanmetzman]

Related: #6180.

[inferno-chromium]

Will we get rid of Dockerfile changes we did in those projects after this stablizes.

[jonathanmetzman]

Will we get rid of Dockerfile changes we did in those projects after this stablizes.

I don't think so. Most of them are necessary to build on Ubuntu 20.04,
Why?

[inferno-chromium]

Will we get rid of Dockerfile changes we did in those projects after this stablizes.

I don't think so. Most of them are necessary to build on Ubuntu 20.04,
Why?

I was confused before with this block (i thought base-builder was old, and 20.04 is something else, but i read the block properly now). looks like base-builder is 20.04 now and 16.04 will be explcit with :xenial, so this is all fine, ignore my comment.

# Using Ubuntu 16.04 because of breakage on Ubuntu 20.04.
# See https://github.com/google/oss-fuzz/issues/6291 for more details.
FROM gcr.io/oss-fuzz-base/base-builder:xenial
# Delete line above and uncomment line below to upgrade to 20.04.
# FROM gcr.io/oss-fuzz-base/base-builder

[jonathanmetzman]

Will we get rid of Dockerfile changes we did in those projects after this stablizes.

I don't think so. Most of them are necessary to build on Ubuntu 20.04,
Why?

I was confused before with this block (i thought base-builder was old, and 20.04 is something else, but i read the block properly now). looks like base-builder is 20.04 now and 16.04 will be explcit with :xenial, so this is all fine, ignore my comment.

# Using Ubuntu 16.04 because of breakage on Ubuntu 20.04.
# See https://github.com/google/oss-fuzz/issues/6291 for more details.
FROM gcr.io/oss-fuzz-base/base-builder:xenial
# Delete line above and uncomment line below to upgrade to 20.04.
# FROM gcr.io/oss-fuzz-base/base-builder

I was also confused. I didn't really consider these when I was thinking of the fixes.
These will be upgraded by the maintainers hopefully soon. Eventually we may force them off.

[oliverchang]

This needs to wait a few more hours before landing as the ClusterFuzz bot updates are still happening. We might also need to revert #6304 for now as that is dependent on this one.