Buildpacks produce quite big image

[andrejusc]

Hi,

I'm comparing image I'm building directly with Docker file like such with Rust static executable inside it:

FROM scratch
COPY target/x86_64-unknown-linux-gnu/release/function /function
CMD [ "/function" ]

where I'm getting as output - image of about 14MB in size:

$ podman image ls | grep sample
localhost/sample                                                   latest         9f76d50aaa01  8 minutes ago  13.9 MB

and layers:

$ podman history sample
ID            CREATED        CREATED BY                                     SIZE        COMMENT
8144b031a549  8 minutes ago  /bin/sh -c #(nop) CMD [ "/function" ]          0 B         FROM 8144b031a549
<missing>     8 minutes ago  /bin/sh -c #(nop) COPY file:3b28c741a95a71...  13.9 MB   

And then I have image for same Rust function produced via buildpacks - about 107MB:

$ podman image ls | grep buildpack-sample
localhost/buildpack-sample                                         latest         181d2f0215c3  43 years ago    107 MB

and layers in it:

$ podman history buildpack-sample
ID            CREATED       CREATED BY  SIZE        COMMENT
181d2f0215c3  43 years ago              3.07 kB     
<missing>     43 years ago              4.1 kB      
<missing>     43 years ago              2.31 MB     
<missing>     43 years ago              2.56 kB     
<missing>     43 years ago              362 kB      
<missing>     43 years ago              27.6 kB     
<missing>     43 years ago              12.8 MB     
401511bdd9f6  43 years ago              2.56 kB     
<missing>     43 years ago              4.61 kB     
<missing>     43 years ago              4.1 kB      
<missing>     43 years ago              25.9 MB     
<missing>     43 years ago              3.07 kB     
<missing>     43 years ago              3.07 kB     
<missing>     43 years ago              65.5 MB     

What is the cause of such big difference? Any specific setting/config to tweak somewhere to make it smaller via buildpacks as well?

[andrejusc]

@dmikusa - appreciate extra feedback.